This invention relates to a motor controller system for battery-powered motors which measures the impact of loads on a motor and its battery at specific instances and, through application of an algorithm and related control parameters, calculates the necessary adjustments to motor speed and torque and corresponding battery use to maximize motor efficiency and extend battery life.
Many battery-operated appliances and small vehicles are being marketed today in place of those powered manually or by a small internal combustion engine, which is inefficient and produces a high level of emissions. Lawn mowers, power garden tools, other power tools, bicycles, wheel chairs and golf carts are among such examples. These devices and vehicles are typically driven by a brushed direct current (xe2x80x9cdcxe2x80x9d) motor, which is directly connected with a lead-acid rechargeable battery through a simple on/off switch. Typically, no means of power control is provided. As a result, the motor runs at high speeds when the battery is fully charged, wasting the battery power. As the battery is drained, the motor voltage drops and the motor speed decreases below the optimal operating speed, causing inefficiency in battery use. As part of this process, the battery may be drained to a low voltage level which causes an irrecoverable damage to the battery. Further, such motors have no means of adjusting power and speed in response to various load factors, which causes further inefficiencies in motor and battery usage between charges. Battery management systems have been developed for low power systems such as laptop computers and wireless phones. Also, various control schemes are implemented for electric and hybrid electric vehicles that employ traction motors of tens of kilowatts or higher. However, an inexpensive battery-powered control system that handles power in the range of several hundred watts and further takes into account of the characteristics of the power loads has not been available. Applications for such a battery-powered control system include: (a) an electric bicycle, (b) an electric vehicle, (c) a hybrid electric vehicle, (d) a three-wheeler (electric), (e) a hybrid three-wheeler, (f) a battery-operated lawn mower, (g) a battery operated golf cart, (h) a battery-operated wheel chair, (i) a battery-operated go-cart, and (j) battery-operated garden or power tools.
For example, battery-operated lawn mowers are currently marketed which employ no means of motor control as disclosed by the present invention. Various load factors impact on the operation of the motor and battery, including condition of the grass and the speed at which the mower is pushed. Without a means to compensate for the impact of these load factors, motor efficiency and battery life are negatively effected.
Similarly, an electric bicycle will experience load or drains on its battery in connection with the power necessary to overcome (a) rolling resistance, (b) drag resistance and (c) climbing resistance. Additionally, power is needed, and corresponding motor/battery load results in connection with acceleration of the bicycle. Finally, power can be added to a bicycle through human assistance and also from regenerative braking which can also add power to the motor/battery system. No system currently exists which measures each of these factors and provides corresponding control to the motor and battery system.
Accordingly, it is the object of the present invention to provide an inexpensive means for controlling a battery-operated dc-motor system to promote motor efficiency and extend battery life. More specifically, the present invention provides a novel motor controller system for battery-powered motors which measures the impact of loads on a motor and its battery at specific instances and, through application of an algorithm and related control parameters, calculates the necessary adjustments to motor speed and torque and corresponding battery use to maximize motor efficiency and extend battery life.